Organic Light Emitting diodes (OLED) devices are comprised of two electrodes and an organic light emitting layer. The organic layer is disposed between the two electrodes. One electrode is the anode and the other electrode is the cathode. The organic layer is structured such that when the anode has a voltage bias that is sufficiently positive relative to the cathode, holes are injected from the anode and electrons are injected from the cathode. The necessary voltage bias depends upon the materials used for the organic layers. The holes and electrons recombine within the organic layer to induce an exited state in a molecule comprising the organic layer. Light is emitted during the process of excited molecules relaxing to their ground state. The anode is typically manufactured from a high work function material such as a Transparent Conducting Oxide (TCO), and the cathode is typically manufactured from a highly reflecting material such as aluminum or silver. However, there exist many different electrode designs which allow light to exit the cathode, the anode, or through both the cathode and the anode. The organic layer can be comprised of a single organic film, or it can be comprised of a stack of multiple organic films. OLED devices are useful as indicators and displays can be constructed from patterned arrays of OLED devices.
Capacitive switching devices operate by sensing a change in capacitance. Touch sensors are capacitive switching devices that operate by sensing the change in capacitance of an electrode with respect to ground. These types of sensors typically sense the change in capacitance caused by the proximity of an operator's finger. Capacitive switching devices can also function by sensing the capacitance or change in capacitance between two conductive objects.
U.S. Pat. No. 7,242,393 B2 discloses a combined OLED capacitive touch sensor and separately discloses the use of configurations and structures that provide tactile feedback. U.S. Patent application publication US 2005/0088417 A1 discloses a tactile touch sensing system that uses a capacitive sensor.